Evidence for the induction of a tumour associated cell surface protease oncytologically normal epithelial cells present in the sputum of patients possessing lung tumours

Sputum obtained from healthy subjects and patients with known lung tumours has been challenged with fluorescent probes for the presence of an active c ell surface protease. The mature epithelial cells from healthy patients' sp utum lacked ability to bind these fluorescent probes whilst the majority of mature epithelial cells in the tumour patients' sputum bound these probes and consequently fluoresced. This demonstrable difference in the cell surfa ce chemistry of mature epithelial cells was linked to the presence of lung tumour cells, which also possessed this cell surface protease. The mechanis m of this induced cell surface enzyme appearance is not understood.